HPTN 052 study stopped early: significant reduction in HIV transmission from early use of HIV treatment in serodifferent partners

Although more detailed results have since been presented (see report from IAS Rome conference earlier in this issue), the following summary information was reported as a press release from the US NIAID.

Initiation of Antiretroviral Treatment Protects Uninfected Sexual Partners from HIV Infection (HPTN Study 052): 96% reduction in HIV transmission, according to study conducted by HIV Prevention Trials Network

Men and women infected with HIV reduced the risk of transmitting the virus to their sexual partners through initiation of oral antiretroviral therapy (ART), according to findings from a large multinational clinical study conducted by the HIV Prevention Trials Network (HPTN), a global partnership dedicated to reducing the transmission of HIV through cutting-edge biomedical, behavioral, and structural interventions.

The study, known as HPTN 052, was designed to evaluate whether immediate versus delayed use of ART by HIV positive individuals would reduce transmission of HIV to their HIV-uninfected partners and potentially benefit the HIV positive individual as well. Findings from the study were reviewed by an independent Data and Safety Monitoring Board (DSMB).The DSMB recommended that the results be released as soon as possible and that the findings be shared with study participants and investigators. The DSMB concluded that initiation of ART by HIV-infected individuals substantially protected their HIV negative sexual partners from acquiring HIV infection, with a 96 percent reduction in risk of HIV transmission. HPTN 052 is the first randomised clinical trial to show that treating an HIV-infected individual with ART can reduce the risk of sexual transmission of HIV to an uninfected partner.

HPTN 052 began in April 2005 and enrolled 1,763 HIV serodifferent couples (couples that have one member who is HIV positive and the other who is HIV negative), the vast majority of which (97 percent) were heterosexual. The study was conducted at 13 sites across Africa, Asia and the Americas. The HIV positive person was required to have a CD4 cell count between 350-550 per cubic millimeter (cells/mm3) at enrolment, and therefore did not require HIV treatment for his or her own health. Couples were randomised to one of two groups. In one group, the HIV positive person immediately began taking ART (immediate ART group). In the other group, the HIV positive person began ART when his or her CD4 cell count fell below 250 cells/mm3 or if he/she developed an AIDS-related illness (the delayed ART group).

Throughout the study, both groups received HIV-related care that included counseling on safe sex practices, free condoms, treatment for sexually transmitted infections, regular HIV testing, and frequent evaluation and treatment for any complications related to HIV infection. Each group received the same amount of care and counseling. Any HIV negative person who became HIV positive during the course of the study was referred to local services for appropriate medical care and treatment.

In its review, the DSMB found a total of 39 cases of HIV infection among the previously uninfected partners. Of those, 28 were linked through genetic analysis to the HIV positive partner as the source of infection. Seven infections were not linked to the HIV positive partner, and four infections are still undergoing analysis. Of the 28 linked infections, 27 infections occurred among the 877 couples in which the HIV positive partner did not begin antiretroviral therapy immediately. Only one case of HIV infection occurred among those couples where the HIV positive partner began immediate antiretroviral therapy. This finding was statistically significant and means that earlier initiation of antiretrovirals led to a 96 percent reduction in HIV transmission to the HIV negative partner. The infections were confirmed by genetic analysis of viruses from both partners.

Additionally, 17 cases of extrapulmonary tuberculosis occurred in the HIV positive partners in the deferred treatment arm compared with three cases in the immediate treatment arm, a statistically significant difference. There were also 23 deaths during the study. Ten occurred in the immediate treatment group and 13 in the deferred treatment group, a difference that did not reach statistical significance.

The press release noted that the ongoing international clinical study called Strategic Timing of Antiretroviral Therapy (START) also funded by NIAID is examining the optimal time for asymptomatic HIV positive individuals to begin antiretrovirals.

Source: NIAID Press release. (12 May 2011)

For additional information about the HPTN 052 study, see the Questions and Answers information on the NIAID website.

Links to other websites are current at date of posting but not maintained.